Hi everyone,
Thank you for letting me know.
I ended up buying a 512GB SDHC Kingston card, formatted it to FAT32 format, then put Rockbox onto it.
Next I bought a SD card to CF card adapter which supports up to 512GB.
Next I bought a CF card to 50 pin IDE adapter then put it all together.
I can confirm this mod works as it boots into Rockbox fine with 512GB.
I seem to have faster read and write speeds then my SSD and the battery seems to last a little longer, not to sure why that is though!
Is there anyway I can add a picture of it on here?
Please let me know?